The symbol: <-> means that the Connector Pin # will have one of two different wires DEPENDING on the actual year of your vehicle or whether your it's equipped with a 4.3L, 5.0L, 5.7L, etc.

C1 (Blue) PCM 32 Pin Connector

Pin

Wire Color

Description

1

---

Empty

2

---

Empty

3

Brown w/ White stripe

1X Cam (CMP) Sensor Signal

4

---

Empty

5

---

Empty

6

---

Empty

7

Tan

HO2S Low Bank 2 Sensor 1

8

Pink w/ Black stripe

Cam (CMP) Sensor Ground (Low)

9

Purple

Fuel Gauge (Fuel Level Output)

10 <->

---

Empty (1998 Only)

10 <->

Tan w/ Black stripe

TCC Control Solenoid (1999 Only)

11

---

Empty

12

---

Empty

13

---

Empty

14

Brown

AIR Relay Control (California Only)

15

Yellow w/ Black stripe

Vehicle Speed Sensor (VSS)

16

---

Empty

17

---

Empty

18 <->

Purple w/ White stripe

Dual Tank Fuel Module (1998 Only)

18 <->

---

Empty (1999 Only)

19

Purple w/ White stripe

HO2S High Bank 1 Sensor 1

20 <->

Purple

HO2S High Bank 1 Sensor 2 (1998 Only)

20 <->

Purple

HO2S High Bank 2 Sensor 2 w/out C6P -under 8600 GVW (1999 Only)

20 <->

Purple

HO2S High Bank 1 Sensor 2 w C6P -over 8600 GVW (1999 Only)

21

Purple

HO2S High Bank 2 Sensor 1

22 <->

Purple w/ White stripe

HO2S High Bank 2 Sensor 2 (1998 Only)

22 <->

Purple w/ White stripe

HO2S High Bank 2 Sensor 2 w/ C6P -over 8600 GVW (1999 Only)

22 <->

Purple w/ White stripe

HO2S High Bank 1 Sensor 2 w C6P -under 8600 GVW (1999 Only)

23

---

Empty

24 <->

Tan

HO2S Low Bank 1 Sensor 2 (1998 Only)

24 <->

Tan

HO2S Low Bank 2 Sensor 2 w/out C6P -under 8600 GVW (1999 Only)

24 <->

Tan

HO2S Low Bank 1 Sensor 2 w/ C6P -over 8600 GVW (1999 Only)

25

Tan w/ White stripe

HO2S Low Bank 1 Sensor 1

26 <->

Tan w/ White stripe

HO2S Low Bank 2 Sensor 2 (1998 Only)

26 <->

Tan w/ White stripe

HO2S Low Bank 2 Sensor 2 w/ C6P -over 8600 GVW (1999 Only)

26 <->

Tan w/ White stripe

HO2S Low Bank 1 Sensor 2 w/out C6P -under 8600 GVW (1999 Only)

27

---

Empty

28

Purple

Crank (CKP) Sensor Ground (Low)

29

Light Green w/ Black

Vehicle Speed Sensor (VSS) Low

30

Purple w/ White stripe

Vehicle Speed Sensor (VSS) Signal

31

Yellow

4X Crank (CKP) Sensor Signal

32

---

Empty

Safety Precautions

Here are some very important safety precautions when testing the wires coming out of the PCM connectors.

If one or any of the wires on your GM vehicle DO NOT match the color stated in the Pin Out Charts... then you should not use the Pin Out charts in this article. Why? Because this is the clearest indication that these ARE NOT the Connector Pin Out Charts for your particular vehicle.

Never probe the front of the Connector.

You should use a Wire Piercing Probe and probe the wire a few inches away from the connector.

I've spent many an hour double, triple, and quadruple checking these pin out charts (in these page and in the next couple of pages) using the best sources to compile it... but nothing in life is perfect. I don't have a staff of proof readers or editors (or even volunteers)... I'm just a little guy typing this stuff up in my spare time to help and give back to the Do-It-Yourself community. So without further ado, here's my disclaimer: